High-frequency system



Filed Nov. 26, 1924 mmzuauxu a R my RE E ONMW M MO EU /T v m Wm. a 4L Umm 5 Patented Mar. 3, 1931 UNITED STATES PATENT OFFICE SAMUEL TURNER, OFBERKS, ENGLAND, ASSIGNOR TO RADIO CORPORATION OF AMERICA, A CORPORATIONOF DELAWARE HIGH-FREQUENCY SYSTEM Application filed November 26, 1924,'Serial No. 752,428, and in Great Britain December 20, 1923.

This invention relates to high frequency telephony whether wireless orwired wireless. In the case of two telephone exchanges connected by avhigh frequency trunk it is desir- I able that the operators shall beable by the usual operations, that is, the operations that would beemployed if the stations were connected by an ordinary telephone trunk,to start and stop the generation of the carrier waves :and to give thecalling and clearing signals and that false calls shall not be given.

The object of this invention is to provide asystem having thesedesiderata even when the high frequency station is at a distance fromthe exchange.

According to this invention the generation of the carrier wave isstarted by a relay, hereinafter called the starting relay, the circuitof which is controlled by a relay, hereinafter called the control relay,the circuit of which is in turn under the control of a slow releaserelay which is energized on the receipt of waves from the distantstation.

The invention is illustrated by the accompanying diagram, in which Fig.1 diagrammatically illustrates a telephone exchange according to myinvention and 2 diagrammatically illustrates a system comprising twosuch telephone exchanges. Referring more particularly to Fig. 1 Trepresents a wireless transmitting station and R a wireless receivingstation. The generation at T of the carrier wave is controlled bv arelay E which is operated by a starting relay S R at a telephoneexchange, the circuit of this relay S R- being under the control of arelay C. The receipt of the carrier wave from a distant station at Rcauses a receiving relay A to energize and thus to connect R to theexchange through a cable, not shown.

Vhen an operator at an exchange Y wishes to call an exchange Z sheinserts a plug 1 into a jack 2 and through the sleeve of her jackenergizes relay C 0. Relay C O energizing completes the circuit ofstarting relay S R through the back contact of control relay C and alsoprepares the circuit of a slow release relay D. S R on energizingcompletes through the cable the circuit of relay E which 0 on energizingcauses the carrier wave to be transmitter. This carrier wave is receivedat the wireless station of exchange Z and actuates relay A whichcompletes a circuit through the cable connecting that station toexchange Z and through call relay B in the exchange. This relay onenergizing completes the circuit of a calling lamp C L. The operator atexchange Z plugs into a jack and causes the emission of a carrier wavefrom the transmitting aerial of exchange Z in exactly the same way asthe emission of the wave from exchange Y was effected.

The receipt of the waves at exchange Y causes relay B to be actuated butinasmuch as the circuit of the slow release relay D had been prepared asabove stated this relay energizes and breaks the circuit of lamp C L sothat no calling signal is given at exchange Y.

Conversation can now take place between the two operators or betweensubscribers to whom they may extend the connection.

At the end of the conversation one of the operators, we will suppose theoperator at exchange Z removes her plug from its jack, C O and S Rtherefore release, and consequently the emission of the carrier wavefrom the station at Z is stopped. The circuit of relay D is thereforebroken at exchange Y, but its armature still remains for a moment on itsfront contact and thus the circuit of relay C is completed. This relayon becoming energized. completes a circuit through the clearing signal 0Z of exchange Y, breaks the circuit of relay S R and completes a lockingcircuit for itself, so that when the armature of relay D drops backcontrol relay C remains energized and relay S R remains de-energized.Thus after a short interval of time from the removal of the plug atexchange Z, the transmitter at exchange Y has beenautomaticallydisconnected, but it will be evident that during this interval of time,the transmitter at Y will be sending out waves to exchange Z. But thiswill not cause a false call as D being slow to release has locked itselfin a circuit through aback contact of C O and a front contact of B. Thusthe withdrawal of the plug at either exchange automatically shuts downboth the Wireless transmitters and gives the clearing signal at theother exchange.

, is restored to normal and she can therefore initiate a fresh call byreinserting her plug into its jack.

Thus supposethat after a conversation the operator at Y clears first,but is about to call again before the Z operator removes her plug.

On receipt of the clear signal and just before the second call from Ythe conditions at'Z will be plugged in, e Z lighted, C O and C operated,A, B, D, S R, '15 and O L disconnected. lVhen Y calls her carrier wavewill operate relays A and B at exchange Z and so the eventual removal ofthe plug by the Z operator will release C O and G and the circuit of C Lwill be completed. g

It is obvious that the relays 'A and B can be arranged so as to beoperated only on the receipt of a modulated signal instead of on receiptof a carrier wave, as previously described.

The arrangement described above can be employed in any type of telephoneexchange.

Having described my invention what I claim is: 1

1. In a high frequency duplex telephone installation, the combination oftelephone exchange, transmitting and receiving stations in connectiontherewith, a starting relay at the exchange whereby the transmitter isset in action, a control relay controlling the circuit of the startingrelay, and a slow release relay energized on the receipt at thereceiving station of oscillations from a distant station and.controlling the circuit of the control relay.

2. A telephone system comprising a pair of telephone stations and aduplex radio circuit therebetween, said telephone stations comprisingrespectively a transmitting device, a

receiving device, a starting relay controlling said transmitting device,a call. relay operated by said receiving device, a control relay forbreaking said starting relay when said call relay is broken, a call lampassociated'with said call relay and clearing lamp associated with saidcontrol relayjwhereby said call lamp is lighted when said call relay isfirst energized and said clearing lamp is lighted circuit, manuallyoperable means for completing said last named circuit, a call relaycircuit operated by said receiving device, a calling lamp circuitadapted to be completed break said rting relay circuit.

circuit are completed, and a control relay circult for said startinrelay circuit adapted to be completed by tne breaking of said call relaycircult and before SFJd SlOW .1'elease relay operates, said controlrelay acting to complete a locking circuit for itself and to A.telephone system comprising a pair of telephone stations and a duplexradio circuit therebctween, said telephone stations coinprisingrespectively a transmitting device, a receiving device, a starting relayfor controlli. g said transmitting device, a control relay "for brea"ing said starting relay, a-call relay operated by said receivingdevice,and a slow release relay energized when said call relay and said controlrelay are completed, said control relay being energized by the breakingof said call relay through the slow action of said'slow release relaywhereby said starting relay is broken. I

5. A telephone system comprising a pair of telephone stations andaduplex radio circuit therebetween, said telephone stations comprisingrespectively av transmitting device, a receiving device, a startingrelay for controlling said transmitting device, a control relay forbreaking said starting relay, a call relay adapted to be completed bysaid receiving device, a slow acting relay adapted to be broken whensaid call relay is broken and a lamp adapted to be lighted when saidcall relay is broken, said control relay being energized by the breakingof said call relay due to the slow action of said slow acting relay, andsaid control relay acting upon energization to break said starting relayand to complete the circuit of said lamp.

SAMUEL TURNER.

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